1. CHAPTER 2 Structure of Solid
Dr. Syafiqah Saidin
CHAPTER 2 Structure of Solid
SMBE3313
2017/2018 Semester 1

2. Bonding Energy / Potential Energy
Dr. Syafiqah Saidin
OUTLINE
Introduction to Solid
Atomic Structure
Bonding Energy / Potential Energy
Ionic Bonding
Covalent Bonding
Metallic Bonding
Secondary Bonding

3. Introduction to Solid Solid
Dr. Syafiqah Saidin
Introduction to Solid
Solid
State of matter with its constituent atoms held together by strong interatomic forces
Interatomic forces
Ionic bonding
Covalent bonding
Metallic bonding
Primary
Strong interatomic force

4. Atomic Structure Atom : Electron = 9.11 x 10-31 kg Proton Neutron
Dr. Syafiqah Saidin
Electron (ē)
Atom :
Electron = 9.11 x kg
Proton
Neutron
Atomic number = No of protons in nucleus of atom /
No of electrons of neutral species
Atomic mass (A) = N + Z
Neutron (N)
1.67 x kg
Proton (Z)
Atomic mass unit (amu) = 1/12 mass of carbon, C-12
Molecular weight/molar mass (g/mol) = Weight of atomic particles
1 amu/atom = 1 g/mol
C has been set as the standard international reference
• Bohr Atomic Model: Electrons are assumed to revolve around the atomic nucleus in discrete orbitals
•Describe electrons in atoms in terms of both position (electron orbitals) and energy

5. Electron at the outermost orbital
Atomic Structure
Dr. Syafiqah Saidin X A
Atomic mass
Isobar : Same A, different Z
Isotope : Same Z, different N
Isotone : Same N
Element Z
No of protons
Electron (ē)
Neutron (N)
Valence electron
Electron at the outermost orbital
Orbital
Proton (Z)
Bohr atom model

6. Atomic Structure Electron energy state
Dr. Syafiqah Saidin
Atomic Structure
Electron energy state
Occupy the atomic no. at the lowest energy state to higher energy state
Low
K shell
L shell
M shell
N shell
n= principal quantum no; shell or energy level
l= orbital momentum quantum no; subshell of electron; s=0; p=1; d=2; f=3 so forth
Ml= magnetic quantum no; orbital of a given subshell; -l<x<+l
Ms= spin magnetic quantum no; +1/2 / -1/2
Aufbau principle: 1s<2s<2p …
Madelung rule: dalam figure
No. of electron can occupy each orbital:
s = 2; p = 6; d = 10; f = 14
High

7. Atomic Structure Ex: Electron energy state of several elements
Dr. Syafiqah Saidin
Ex: Electron energy state of several elements

8. Atomic Structure Exercise
Dr. Syafiqah Saidin
Exercise
Write the electron energy state for the following elements:
Sodium, Na
Magnesium, Mg
Titanium, Ti
Fluorine, F
Chlorine, Cl
Na, 11=1s2 2s2 2p4 3s2 3p1; valence=3
Mg, 12=1s2 2s2 2p4 3s2 3p2; valence=4
Ti, 22=1s2 2s2 2p4 3s2 3p2 4s2 3d8; valence=12
F, 9=1s2 2s2 2p4 3s1; valence=1
Cl, 17

9. Periodic Table Inert gas Give 1ē Give 2ē Receive 2ē Receive 1ē
Dr. Syafiqah Saidin
Inert gas
Give 1ē
Give 2ē
Receive 2ē
Receive 1ē

10. Periodic Table Electronegativity: Ranges from 0.7 to 4.0
Dr. Syafiqah Saidin
Electronegativity:
Ranges from 0.7 to 4.0
Higher electronegativity – Higher tendency to receive electrons
Increase electronegativity

11. Bonding Energy / Potential Energy
Dr. Syafiqah Saidin
Bonding Energy / Potential Energy
When two atoms are close, both of them are under the influence of two forces:
Attractive force – The force that attract both atoms to be closed
Repulsive force - The force by the positive charges that push away one atom to another

12. Bonding Energy / Potential Energy
Dr. Syafiqah Saidin
Bonding Energy / Potential Energy
Net energy, EN = Repulsive energy, ER + Attractive energy, EA
Repulsive force : Dominates at small distance
Attractive force : Dominates at larger distance
At equilibrium : Both are equal
Low energy : The element is more stable

13. Bonding Energy / Potential Energy
Dr. Syafiqah Saidin
Bonding Energy / Potential Energy
Tm : Melting temperature
Eo : Elastic modulus / Young’s modulus
Relation between bonding energy and melting temperature
Relation between bonding energy and elastic modulus

14. Bonding Energy / Potential Energy
Dr. Syafiqah Saidin
Bonding Energy / Potential Energy
Force
Deformed metal + +
Force
High attraction force, low repulsive force
Low attraction force, high repulsive force

15. Bonding Energy / Potential Energy
Dr. Syafiqah Saidin
Bonding Energy / Potential Energy
Relation between bonding energy and melting temperature
Bonding Type
Substance
Bonding energy
(kJ/mol)
Melting temperature
Ionic
NaCl
640
801
MgO
1000
2800
Covalent Si
450
1410
Diamond
713
>3550
Metallic Al
324
660 Fe
406
1538
Van der Waals Ar
7.7
-189
Cl2 31
-101
Bonding energy Melting temperature

16. Ionic Bonding Metallic compound Non-metallic compound Donate electron
Dr. Syafiqah Saidin
Metallic compound
Donate electron
Non-metallic compound
Accept electron ē
Transferring free valence electron to be stable
Metallic Mg Cl + -
Cation
Anion
Electrostatic force / Coulomb effect
Ex : Mg+ ion
Ex : Cl- ion

17. Dr. Syafiqah Saidin
Ionic Bonding
In solid state, cations are occupied/surrounded by as many anions to reduce repulsion force between cations, thus leading to solid arrangement of a crystal structure
Ionic solid is a poor electrical conductor since electrons are no longer carry charge (have difficulties in carry charge) due to tight molecule arrangement.
Ex: NaCl, MgO, AgCl, etc

18. Ionic Bonding Typical metal crystal structure
Dr. Syafiqah Saidin
Typical metal crystal structure
Au = 3 atoms in each unit cell; Fe = 2
Exercise: Gold (Au) and iron (Fe) have FCC and BCC crystal arrangements, respectively, how many atoms in each unit cell?

19. Ionic Bonding Exercise
Dr. Syafiqah Saidin
Exercise
1. Calculate the density of metallic Fe if the edge length of a unit cell is pm.
Given :
Avogadro no. = 6.02 x 1023 atoms/mol
Molecular weight = g/mol
7.87 g/cm3

20. Ionic Bonding Exercise
Dr. Syafiqah Saidin
Exercise
2. The density of nickel is g/cm3. If the metallic radius of nickel is 125 pm, what is the structure of metallic nickel? Atomic weight, Ni = 58.69
3. Lithium crystallizes in a bcc structure with an edge length of Å. Calculate its density. What is the approximate metallic radius of lithium in picometers? Atomic weight, Li : 6.94 g/mol
Fcc
d =  g/cm3, r =151.9 pm

21. Ionic Bonding Transfer electron Receive electron Dr. Syafiqah Saidin

22. Covalent Bonding
Dr. Syafiqah Saidin
Mostly involves elements in the middle of periodic table which have tendency to donate and receive electrons
Bonding principle: sharing valence electrons
Ex: Methane, CH4 C H
C has 4 valence electrons to be shared
H has 2 valence electrons to be shared

23. Ex: Diamond, silicon, graphite
Covalent Bonding
Dr. Syafiqah Saidin
In a large group, the atoms often form a tetrahedron arrangement, lead to orderly repeating pattern
Localization of valence electrons cause these materials to be poor electrical conductor too
Ex: Diamond, silicon, graphite
Graphite
arrangement
Diamond
arrangement
Diamond : cubic; graphite : hexagonal

24. Covalent Bonding Mostly column IVA Dr. Syafiqah Saidin

25. Metallic Bonding
Dr. Syafiqah Saidin
For strong metal electron donor, they are bonded through metallic bonding instead of ionic and covalent bonding
Most metals have high melting point due to this strong bonding
Metal atoms are arranged in 3D repeating order, closely packed where its valence electrons are floating between atoms like a gas
Delocalised electrons +
Positive charge metal ions
Metallic bonding structure

26. Dr. Syafiqah Saidin
Metallic Bonding
Electrical charge are neutralized within the crystal structure where negative charge behaves like a glue between the positive charge core.
Metal is possibly be deformed and deployed due to this metallic bonding arrangement
Force + +
Force
Deformed metal

27. Secondary bonding Van der Waals bonding:
Dr. Syafiqah Saidin
Secondary bonding
Van der Waals bonding:
Binding forces between atomic group or molecules other than the ionic, covalent and metallic bonding
3 – 10% weaker than the primary bonding
Normally arise between the covalent bonding among molecules and between dipoles
It doesn’t have direction
Strong attraction between near molecules compared to farther molecules

28. Covalent bonding Van der Waals bonding Water, H2O Dr. Syafiqah Saidin

29. Dr. Syafiqah Saidin